Amounts Of Atmospheric Carbon Dioxide Research Articles

Reading Between the Lines: Investigating the Ability of JWST to Identify Discerning Features in exoEarth and exoVenus Transmission Spectra

The success of the Transiting Exoplanet Survey Satellite mission has led to the discovery of an abundance of Venus Zone terrestrial planets that orbit relatively bright host stars. Atmospheric observations of these planets play a crucial role in understanding the evolutionary history of terrestrial planets, past habitable states, and the divergence of Venus and Earth climates. The transmission spectrum of a Venus-like exoplanet can be difficult to distinguish from that of an Earthlike exoplanet however, which could severely limit what can be learned from studying exoVenuses. In this work we further investigate differences in transmission between hypothetical exoEarths and exoVenuses, both with varying amounts of atmospheric carbon dioxide (CO2). The exoEarths and exoVenuses were modeled assuming they orbit TRAPPIST-1 on the runaway greenhouse boundary. We simulated James Webb Space Telescope Near-Infrared Spectrograph PRISM transit observations of both sets of planets between 0.6 and 5.2 μm, and quantified the detectability of major absorption features in their transmission spectra. The exoEarth spectra include several large methane (CH4) features that can be detected in as few as six transits. The CH4 feature at 3.4 μm is the optimal for feature for discerning an exoEarth from an exoVenus since it is easily detectable and does not overlap with CO2 features. The sulfur dioxide (SO2) feature at 4.0 μm is the best indicator of an exoVenus, but it is detectable in atmospheres with reduced CO2 abundance.

Species Diversity and Carbon Stock of Mangrove in Guiuan, Eastern Samar, Philippines

Mangrove forests sequester substantial amounts of atmospheric carbon dioxide, store carbon in their biomass, and have the highest carbon pool of any forest. The Philippines is one of the mangrove-rich countries, with almost 1.9% of the global mangroves. No current published works on mangroves exist in Guiuan, Eastern Samar, Philippines. This study utilized a non-destructive technique through quadrat sampling to identify and measure mangroves’ biodiversity and carbon stock. The allometric equation was applied to quantify the carbon stock and Shannon-Wiener diversity index to determine the biodiversity. Twelve species were identified from the 36 sampling plot with 10 × 10 meter. Results showed the mean species evenness of 0.28 and the Shannon-Wiener diversity value of 0.92, indicating very low diversity. The overall aboveground, belowground, total carbon stock, and CO2 sequestration of 209 t/ha, 76 t/ha, 157 t/ha, and 575 CO2 t/ha, respectively. The test revealed that comparing the six barangays regarding species diversity and carbon stocks gives no statistically significant difference of 0.032 and 0.046, respectively. Considering the estimated carbon stock and CO2 equivalent accounted from the tree biomass, the mangrove stands in Guiuan have the potential to store and sequester a large amount of carbon dioxide.

DESIDROGENAÇÃO CATALÍTICA OXIDATIVA DO ETANO UTILIZANDO CO2: UMA MINI REVISÃO

As a consequence of the greenhouse effect, there is a growing concern worldwide to reduce the amount of atmospheric carbon dioxide and a continuous effort by the scientific community to expand its use in various applications. Recently, CO2 has been used as an alternative, being applied as a light oxidant in the ethane oxidative dehydrogenation reaction, enabling new routes to obtain ethylene that are more efficient and economical than the current ones. Thus, the oxidative dehydrogenation of ethane with carbon dioxide stands out as one of the most promising alternatives, as it is an economical and ecological process, consuming one of the greenhouse gases. To analyze the literature on the relevance of the catalytic oxidative dehydrogenation reaction of ethane as an alternative route to ethylene production. This is a bibliographic review that used as source the databases of ELSEVIER, SPRINGER and CAPES from the descriptors "ODHE", "Oxidative catalytic dehydrogenation with CO2" and "ethene". Using the inclusion criteria, 50 articles in English and Portuguese published from 2012 to 2023 and a technical book were analyzed. CO2 is a promising alternative for the oxidative dehydrogenation reaction of ethane with O2, which suffers from catalyst deactivation due to coke formation and reducing selectivity to the main product. From the use of CO2 as an oxidant in the reaction, we have the advantage of producing active oxygen species, reducing coking and increasing selectivity. However, the great challenge is the development of catalysts that are active and selective to ethylene, with nickel oxide and cerium oxide emerging as promising alternatives, with high catalytic activity and favoring the redox cycle.

Application of agriculture and an industrial by-product as a supplementary cementitious material in binary and ternary blended concrete

The production of ordinary Portland cement [OPC] causes an environmental imbalance of nature by consuming the natural resources and releasing a very high amount of atmospheric carbon dioxide. Therefore it is necessary to find the substitute to cement. Bagasse ash from sugar industries and slag from steel industries are the waste product which is utilized as the supplementary cementitious materials. In this study, sugarcane bagasse ash (SCBA) and ground granulated blast furnace slag (GGBFS) are used to replace cement partially. The fresh and harden properties find out for the M25 grade of concrete. The experimental outcome reveals that binary concrete with 15% bagasse ash and ternary concrete with 20% bagasse ash and 5% slag had maximum strength.

Economics of Soil Carbon and its Specifics in Ukraine

Anthropogenic emissions are one of the main causes of global warming. Carbon dioxide is the most commonly produced greenhouse gas. Sequestration is one of the options to decrease the amount of atmospheric carbon dioxide. One of the main types of carbon sequestration is the biological carbon sequestration method of soil carbon sequestration. There are various estimates of the SCS potential of soils since the knowledge of soil carbon conservation processes is still limited. However, it is evident that degraded soils have more potential to sequester carbon. The aim of the paper is to analyze the social cost of soil organic carbon in soils of Ukraine, discuss different ways used to estimate the price of soil organic carbon and the carbon sequestration potential of different soils. The social cost of carbon was used to estimate the value of soil organic carbon stocks in Ukraine because it shows the avoided social cost of carbon emissions. The social cost of carbon represents the net present value of the climate change impact of additional carbon released into the atmosphere (marginal global damage costs). Estimation of the social cost of SOC stock in different types of soils in Ukraine makes it possible to compare alternative land use options and to make right policy choices. The results depict the high importance of Ukrainian soils in preventing global climate changes through carbon storage. Czornozem soils are especially rich in SOC, and therefore more valuable in terms of the ecosystem services they provide. The sequestration potential of most types of Ukrainian soils exceeds the sequestration potential of forests. The article proposes measures and practices for soil carbon sequestration and SOC protection. The implementation of the measures to preserve and accumulate SOC will contribute to the increase in biological productivity of agricultural soils and, consequently, boost the yield of cultivated crops, which will have a positive effect on food security

Deep carbon export peaks are driven by different biological pathways during the extended Scotia Sea (Southern Ocean) bloom

Estimating the amount of organic carbon leaving the upper water column and becoming sequestered in the deep ocean is a major challenge in our understanding the oceanic C cycle. This study investigate deep sediment trap material collected at a 5 day resolution over a 4 month period covering the bloom in the northern Scotia Sea. This region is characterised by extensive and long-lived phytoplankton blooms that collectively take up the greatest amount of atmospheric carbon dioxide yet measured in the Southern Ocean. In particular, the study resolved multiple peaks of POC flux during the northern Scotia Sea bloom resulting from distinctly different export processes. This work also examine the contribution of diatoms and calcifying species to the POC flux as well as determining FP (faecal pellet) characteristics, including biogeochemical composition and sinking velocity. Results showed that POC flux during the bloom was concentrated in three major POC peak events. The first two POC peaks were large, of similar intensity (24.5 mg C m−2 d−1 in early November and 22.5 mg C m−2 d−1 in early December), and were dominated by faecal pellets (FPs, 60–66%). FP biogeochemical composition during these two POC peaks was characterised by a dominance of carbonate (>48%), as well as a higher sinking speed (up to 347 m d−1) compared with other FP in the rest of the samples. Results suggest that the large presence of calcium carbonate in these FPs contributed to their relatively high sinking velocity which, in turn, promoted their higher level of POC export to bathypelagic depths. Intact single cell diatoms were relatively important in the first POC peak (mainly characterised by Fragilariopsis kerguelensis and Thalassionema nitzschioides), while detritus including semi-grazed phytodetritus were more abundant during the second POC peak, suggesting a change in the upper ocean C cycle between the two POC peaks. A third, smaller, POC peak (12.7 mg C m−2 d−1 in January) was dominated by diatom resting spores, mainly Chaetoceros Hyalochaete sp. (>70% of total diatoms contribution), which were, almost exclusively, fully intact cells. Our high resolution sampling allowed insights into short time-scale processes that influence the ultimate magnitude of the substantial annual POC flux in this region. Overall our findings highlights that the temporal sequence of biological events in the surface layers during the bloom has a strong influence on both the magnitude and the composition of the fluxes.

Net ecosystem exchange of carbon dioxide fluxes and its driving mechanism in the forests on the Tibetan Plateau

Boreal forests sequester massive amounts of atmospheric carbon dioxide (CO2), and the contribution from the mid-high-latitude coniferous forests is considerable. This study quantified the net ecosystem exchange (NEE) of CO2 flux and its driving factors in a spruce forest in the Qilian Mountains. The results indicated that the NEE presented a robust temporal pattern ranging from −26.09 to 12.35 g C m−2 on a day-to-day basis. Furthermore, cumulative monthly NEE flux varied between −194.61 g C m−2 and 33.56 g C m−2. Forest ecosystems are vital carbon sinks that sequester/store carbon dioxide from April to September, especially from June to August. The annual NEE flux was a robust carbon sink of 545.99 g C m−2. Forest NEE was significantly driven by latent heat flux, net radiation, air temperature, and precipitation (P < 0.001). Regression coefficient of fitting model was 49.2% using latent heat flux, air temperature, and precipitation. In addition, future warming and precipitation scenarios may have considerably negative and positive effects, respectively, on the carbon sink.

Remotely Monitoring Vegetation Productivity in Two Contrasting Subtropical Forest Ecosystems Using Solar-Induced Chlorophyll Fluorescence

Subtropical forests can sequester a larger amount of atmospheric carbon dioxide (CO2) relative to other terrestrial ecosystems through photosynthetic activity and act as an important role in mitigating global climate warming. Compared with the model-based gross primary production (GPP) products, satellite-derived solar-induced fluorescence (SIF) opens a new window for quantification. Here, we used the remotely sensed SIF retrievals, two satellite-driven GPP products including MODIS (GPPMOD) and BESS (GPPBESS), and tower-based GPP measurements at two contrasting subtropical forests to provide a systematic analysis. Our results revealed that GPP and the associated environmental factors exhibited distinct seasonal patterns. However, the peak GPP values had large differences, with stronger GPP in the evergreen needleleaf forest site (8.76 ± 0.71 g C m−2 d−1) than that in the evergreen broadleaf forest site (5.71 ± 0.31 g C m−2 d−1). The satellite-derived SIF retrievals showed great potential in quantifying the variability in GPP, especially for the evergreen needleleaf forest with r reaching up to 0.909 (p &lt; 0.01). GPPMOD and GPPBESS showed distinctly different performances for the two subtropical forests, whereas the GPP estimates by exclusive use of satellite-based SIF data promised well to the tower-based GPP observations. Multi-year evaluation again confirmed the good performance of the SIF-based GPP estimates. These findings will provide an alternative framework for quantifying the magnitude of forest GPP and advance our understanding of the carbon sequestration capacity of subtropical forest ecosystems.

Agroforestry for controlling soil erosion and enhancing system productivity in ravine lands of Western India under climate change scenario.

Soil erosion in semi-arid climate leading to the development of ravine lands is the most severe form of land degradation. Ravine lands are formed when soil is not fully covered by the vegetation throughout the year and sporadic vegetation is not able to bind the soil particles from being washed away by rainfall. Throughout the globe, ravine lands have severe limitations for their rehabilitation and sustainable utilization as a consequence of its unique topographical features. Climatic and edaphic stresses make crop production extremely challenging in these lands. Practicing sole cropping promotes erosion, produces low crop yield, utilizes high energy, and emits greenhouse gasses (GHGs). Tree cultivation either sole or in combination with crops (agroforestry) has a strong potential to control erosion, produce sustainable economic yield, reduce energy consumption, and sequester greater amount of atmospheric carbon dioxide in biomass and soil carbon pools besides providing various ecosystem services. Therefore, practicing agroforestry could be a promising approach to obtain the greater environmental and economic benefits in the ravine lands. The present study was conducted on three systems, i.e., sole crop cultivation (cowpea + castor), agroforestry (sapota + cowpea + castor), and sole sapota plantation, to evaluate their impact on soil erosion, runoff, system productivity, profitability, energetics, and carbon sequestration during the 4-year period (2017-2020). The results revealed that agroforestry reduced the total soil loss and runoff by 37.7% and 19.1%, respectively, compared to the sole crop cultivation. Likewise, the highest system productivity as cowpea equivalent yield (CEY) was obtained under agroforestry system that increased the CEY by 162% and 81.9%, compared to sole crop and sole tree plantation, respectively. The climate change mitigation potential in terms of net carbon balance was observed highest in sole tree plantation (8.4 t/ha) followed by agroforestry system (5.9 t/ha) and lowest in sole cropping system (-2.8 t/ha). Therefore, an agroforestry system could be recommended for controlling soil erosion, improving system productivity and profitability, and reducing energy consumption as well as mitigating climate change in ravine lands.

Carbon storage estimation in a secondary tropical forest at CIEE Sustainability Center, Monteverde, Costa Rica

Secondary growth tropical rainforests have the potential to sequester large amounts of atmospheric carbon dioxide and as such are an important carbon sink. To evaluate a local forest, a Carbon Neutrality Program was initiated at the Council on International Educational Exchange, San Luis Campus, Monteverde, Costa Rica. The study was conducted on 50 hectares of forest classified as Premontane Wet Forest. The forest, part of the Arenal-Monteverde Protected Zone, is estimated to be aproximately 50 years old and is in the upper regions of the San Luis valley at 1100 m elevation. Assessment of the carbon stock in trees was carried out in two permanent, 1 hectare plots, 100 m by 100 m, Camino Real and Zapote. The plots were divided into 25 subplots, 20 m by 20 m totaling 400 m2 per subplot. Ten subplots in each area were studied which represented 1.6% the total surface area of the forest. All of the trees were measured within the subplots that had a diameter at breast height ≥ 10 cm and the height of 10% of the trees measured. The estimated total CO2 sequestered by the campus forest was 18,210 ton (in 2019).

Greenhouse Effect in the Standard Atmosphere

The “line-by-line” method is used for the evaluation of thermal emission of the standard atmosphere toward the Earth. Accounting for thermodynamic equilibrium of the radiation field with air molecules and considering the atmosphere as a weakly nonuniform layer, we reduce the emission at a given frequency for this layer containing molecules of various types to that of a uniform layer, which is characterized by a certain radiative temperature Tω, an optical thickness uω and an opaque factor g(uω). Radiative parameters of molecules are taken from the HITRAN database, and an altitude of cloud location is taken from the energetic balance of the Earth. Within the framework of this model, we calculate the parameters of the greenhouse effect, including the partial radiative fluxes due to different greenhouse components in the frequency range up to 2600 cm−1. In addition, the derivations are determined from the radiative flux from the atmosphere to the Earth over the concentration logarithm of greenhouse components. From this, it follows that the observed rate of growth of the amount of atmospheric carbon dioxide accounts for a contribution of approximately 30% to the observed increase in the global atmosphere during recent decades. If we assume that the basic part of the greenhouse effect is determined by an increase in the concentration c(H2O) of water atmospheric molecules, it is approximately dlnc(H2O/dt)=0.003 yr−1. This corresponds to an increase in the average moisture of the atmosphere of 0.2%/yr.

Forest management required for consistent carbon sink in China\u2019s forest plantations

BackgroundForest is the largest biomass carbon (C) pool in China, taking up a substantial amount of atmospheric carbon dioxide. Although it is well understood that planted forests (PFs) act as a large C sink, the contribution of human management to C storage enhancement remains obscure. Moreover, existing projections of forest C dynamics suffer from spatially inconsistent age and type information or neglected human management impacts. In this study, using developed PF age and type maps and data collected from 1371 forest plantation sites in China, we simulated biomass C stock change and quantified management impacts for the time period 2010–2050.ResultsResults show that future forest biomass C increment might have been overestimated by 32.5%–107.5% in former studies. We also found that age-related growth will be by far the largest contributor to PF biomass C increment from 2010 to 2050 (1.23 ± 0.002 Pg C, 1 Pg = 1015 g = 1 billion metric tons), followed by the impact of human management (0.57 ± 0.02 Pg C), while the contribution of climate is slight (0.087 ± 0.04 Pg C). Besides, an additional 0.24 ± 0.07 Pg C can be stored if current PFs are all managed by 2050, resulting in a total increase of 2.13 ± 0.05 Pg C.ConclusionsForest management and age-related growth dominate the biomass C change in PFs, while the effect of climatic factors on the accumulation is minor. To achieve the ambitious goal of forest C stock enhancement by 3.5 Pg from 2020 to 2050, we advocate to improve the management of existing forests and reduce the requests for more lands for forest expansion, which helps mitigate potential conflicts with agricultural sectors. Our results highlight that appropriate planning and management are required for sustaining and enhancing biomass C sequestration in China’s PF.

Viability of greenhouse gas removal via artificial addition of volcanic ash to the ocean

Abstract Mitigating human contributions to climate change is a highly debated topic, as it becomes evident that many nations do not adhere to optional reductions in global emission. Substantial research is taking place into negative carbon technologies that actively reduce the amount of atmospheric carbon dioxide (CO2) via greenhouse gas removal (GGR). Various GGR methods have been proposed, from reforestation to ocean fertilisation. This article discusses advantages of an approach based on enhanced input of tephra to the ocean, to increase the drawdown of atmospheric CO2. Natural addition of tephra to the ocean results in preservation of enhanced organic matter in sediment. Hence, augmenting its delivery should raise the level of sequestration. Calculations indicate that offshore tephra addition could sequester 2750 tonnes of CO2 per 50,000 tonnes of ash delivered (a typical bulk carrier’s capacity). The cost is estimated as ∼$55 per tonne of CO2 sequestered and is an order of magnitude cheaper than many proposed GGR technologies. Further advantages include: tephra addition is simply an augmentation of a natural Earth process, it is a low technology approach that requires few developments, and it may sequester carbon for thousands of years. Hence, offshore tephra addition warrants further investigation to assess its viability.

Recent advances in low-temperature electrochemical conversion of carbon dioxide

Abstract Since the onset of the industrial revolution, fossil fuels have been the primary source of energy generation, and the continued exploitation of fossil fuels has led to an increase in the amount of atmospheric carbon dioxide. A lot of research currently focuses much on decreasing dependence on fossil fuels by replacing them with green energy. However, this technique poses a number of challenges, such as the need for improved infrastructure and technology and the high market penetration of renewable energy technologies. Capturing and converting carbon dioxide using electrochemical approaches can help to stabilize atmospheric greenhouse gas levels and create a positive future for the transformation of carbon dioxide into a number of value-added products. The conversion of carbon dioxide via electrochemical approach is a major challenge, and consideration must be given to the development and production of low-cost, stable, and highly efficient electrocatalysts. Hence, this review presents an overview of the current developments in the electrochemical conversion of carbon dioxide. In addition, this study discusses the current progress of electrocatalysts, in particular, the homogeneous and heterogeneous catalyst, which has a high level of activity and selectivity of low overpotential preferred products. The overview of the mechanisms and kinetics of the carbon dioxide reduction using the computational method are also addressed.

Effect of various fertilizers on yield of green azolla (Azolla pinnata) and its feeding effect on Osmanabadi goat kids

Azolla has great potentiality and its use has been recognized mostly in the East countries and also in India. It has a variety of uses in various fields like poultry, livestock, in the production of biofertilizer and in the cultivation of rice. Making use of the natural symbiotic relationship between various species, the use of Azolla in integrated farming practices as a substitute for chemical fertilizer has been carried out. By this practice, Azolla can be used as a biofuel. This process also helps in the absorption of large amount of atmospheric carbon dioxide thereby reducing the threat of climate change. Based on these properties Azolla‘s value is gradually being recognized in the western countries which see Azolla as a potential source of high value products in pharmacy, bioplastics and nutraceutical industry.

The moderating or amplifying biophysical effects of afforestation on CO2-induced cooling depend on the local background climate regimes in China

Afforestation can significantly influence regional climates through both the biogeochemical and biophysical processes involved in land surface-atmosphere interactions. However, many studies have ignored the biophysical processes that can, in some cases, offset the biogeochemical impacts. In this paper, the amount of atmospheric carbon dioxide absorbed by forests and the surface energy balance changes due to land cover changes from croplands and grasslands to forests were quantitatively analyzed, and the impacts of afforestation on the regional temperatures were thoroughly investigated over various climate zones of China, especially over the temperate and arid regions. According to our analysis, (1) when considering only the CO2-induced effects, afforestation led to carbon sequestration ranging from 267.7 to 531.5 Mg CO2-eq hm−250 yr−1 and carbon sinks ranging from 2.6 to 15.7 Mg CO2-eq hm−250 yr−1 in all climate regions; therefore, the cooling effects were achieved. (2) When considering only the biophysical effects, the increase in the net radiation was greater than the increase in the latent heat fluxes in the arid and semiarid regions. Therefore, the land surface provides a positive heat fluxes to the atmosphere and warms the Earth. In contrast, afforestation leads to a decrease in the net radiation and a large increase in the latent heat flux in humid subtropical regions. The increase in net radiation was less than the increase in the latent heat fluxes over the Tibetan Plateau and mid-temperate humid regions, resulting in atmospheric cooling effects. (3) When considering both the CO2-induced and biophysical effects simultaneously, the potential cooling effects caused by afforestation were amplified 1.3–1.5 times relative to those resulting from considering only the CO2 for the subtropical regions. However, the potential cooling effects in arid and semiarid regions were moderated to only approximately 50% of those when only the CO2 was considered. Therefore, the biophysical processes of afforestation have amplified the CO2-induced changes in the subtropical regions and moderated them in temperate regions, while the reverse is true in arid regions.

Diversity of mangrove vegetation and carbon sink estimation of Segara Anakan Mangrove Forest, Cilacap, Central Java, Indonesia

Widyastuti A, Yani E, Nasution EK, Rochmatino. 2018. Diversity of mangrove vegetation and carbon sink estimation of Segara Anakan Mangrove Forest, Cilacap, Central Java, Indonesia. Biodiversitas 19: 246-252. Mangrove forests are known as standing stores of sequestered atmospheric carbon. The role of mangrove forests in the sequestering substantial amount of atmospheric carbon dioxide (CO2) and storing the carbon in its biomass has been recently underscored. This research aimed to estimate vegetation diversity and carbon sink potential of Segara Anakan Mangrove Forest Cilacap, Central Java from August-December 2012. Vegetations sampling was done by square plots technique. Diversity index was utilized to determine species diversity. Allometric equations were used to estimate biomass and carbon sinks. This study only calculates aboveground biomass and carbon sinks. The research results showed that mangrove in Segara Anakan was composed of 24 species with 19 families, consisting of 16 species of trees, 14 species of saplings and 16 species of herbs. The most dominant tree was Avicennia marina with importance value of 43.62% in Kembang Kuning, 60.27% in Ujung Alang and 25.6% in Klaces. The most dominant of sapling was Avicennia marina, with an important value of 31.1%. The total biomass of a tree is about 43.06 kg/tree or 0.13 ton/ha. Total biomass of sapling was 27.38 kg/tree or 0.32 ton/ha. The carbon sink of the tree was 49.10 ton/ha and carbon sink of sapling was 79.39 ton/ha. It can be concluded that Segara Anakan Mangrove forest is very important as a carbon sink in South part of Central Java, Indonesia.

Characterization model to assess ocean acidification within life cycle assessment

Purpose Ocean acidification due to the absorption of increasing amounts of atmospheric carbon dioxide has become a severe problem in the recent years as more and more marine species are influenced by the decreasing pH value as well as by the reduced carbonate ion concentration. So far, no characterization model exists for ocean acidification. This paper aims to establish such a characterization model to allow for the necessary future inclusion of ocean acidification in life cycle assessment (LCA) case studies.

Evidence for Strain-Specific Exometabolomic Responses of the Coccolithophore Emiliania huxleyi to Grazing by the Dinoflagellate Oxyrrhis marina

The coccolithophore Emiliania huxleyi forms massive blooms and plays a critical role in global elemental cycles, sequestering significant amounts of atmospheric carbon dioxide on geological time scales via production of calcium carbonate coccoliths and emitting dimethyl sulfoniopropionate (DMSP) which has the potential for increasing atmospheric albedo. Because grazing in pelagic systems is a major top-down force structuring microbial communities, the influence of grazers on E. huxleyi populations has been of interest to researchers. Roles of DMSP (and related metabolites) in interactions between E. huxleyi and protist grazers have been investigated, however, little is known about the release of other metabolites that may influence, or be influenced by, such grazing interactions. We used high-resolution mass spectrometry in an untargeted approach to survey the suite of low molecular weight compounds released by four different E. huxleyi strains in response to grazing by the dinoflagellate Oxyrrhis marina. Overall, a strikingly small number of metabolites were detected from E. huxleyi and O. marina cells, but these were distinctly informative to construct metabolic footprints. At most, E. huxleyi strains shared 25% of released metabolites. Furthermore, there appeared to be no unified metabolic response in E. huxleyi strains to grazing; rather these responses were strain specific. Concentrations of several metabolites also positively correlated with grazer activities, including grazing, ingestion, and growth rates; however, no single metabolite responded uniformly across all strains of E. huxleyi tested. Regardless, grazing clearly transformed the constituents of dissolved organic matter produced by these marine microbes. This study addresses several technical challenges, and presents a platform to further study the influence of chemical cues in aquatic systems and demonstrates the impact of strain diversity and grazing on the complexity of dissolved organic matter in marine systems.

Estimation of Stem Carbon Stock of Selected Eucalyptus grandis Plantations in Up Country Sri Lanka

Plantation forestry plays an important role in mitigating global warming and climate change by sequestering carbon dioxide in their biomass. Eucalyptus grandis is an important timber species in plantation forestry in Sri Lanka. The objectives of the present study were to estimate the stem carbon stock, the total amount of atmospheric carbon dioxide sequestered in stems and the monetary value of carbon sequestered in stems of selected E. grandis plantations in upcountry Sri Lanka. Four study sites were selected from Kandapola, Bogawanthalawa, Haputhale and Pinnawala to represent upcountry, intermediate zone and wet zone where E. grandis is confined to. Each plantation was divided into three strata and 0.05 ha circular sample plot was laid out in each stratum. Each individual in the plot was measured for total tree height and diameter at breast height (dbh). The carbon content of each E. grandis stem of individuals in the plantations was calculated using a constructed model to predict stem carbon of E. grandis, in which the explanatory variables are total tree height and dbh. Thereby total stem carbon stock of each plantation was estimated. Total amount of atmospheric carbon dioxide sequestered in all the E. grandis stems of each plantation and monetary value of carbon sequestered in each stem were thereby calculated for each plantation. The lowest value of estimated amount of carbon sequestered in E. grandis stems per hectare was observed in Kandapola plantation (28.176 t/ha) while the highest value was observed in Pinnawala plantation (504.095 t/ha). The highest value of estimated total stem carbon stock of a plantation was observed in Bogawanthalawa plantation (17,390.669 t). For estimated amount of atmospheric carbon dioxide sequestered in E. grandis stems, the lowest value was observed in Kandapola plantation (103.405 t/ha) while the highest value was observed in Pinnawala plantation (1,850.027 t/ha). The highest value of estimated total amount of atmospheric carbon dioxide sequestered in the stems of a plantation was observed in Bogawanthalawa plantation (63,823.757 t). When considering the monetary value of carbon stock in E. grandis stems, the lowest estimated value was observed in Kandapola plantation (3,803.72 Rs./ha) while the highest value was observed in Pinnawala plantation (68,052.76 Rs./ha). When considering plantation wise carbon stock, the highest value of estimated monetary value was observed in Bogawanthalawa plantation (Rs. 2,347,740.37). These estimates shall be presented to assess the carbon dynamics in E. grandis plantations in upcountry Sri Lanka. Keywords: Eucalyptus grandis, Carbon sequestration, Climate change, Carbon stock